Reduction of moire effect in pixelated rear-projection displays

ABSTRACT

An apparatus and method for reducing the moiré effect in rear-projection displays by rotating the dark-stripe structure ( 711, 712 ) in the screen ( 71 ) 45±15 degrees relative to the displayed pixel structure. By rotating the dark-stripes ( 711 ) relative to the displayed pixels, the spatial frequency at which the moiré effect sets in can be improved by 15% to 41%.

FIELD OF THE INVENTION

[0001] The present invention relates to projection displays and morespecifically to reducing the moiré effect associated withrear-projection displays based on pixelated technologies, such as DMD,LCD, LCOS, etc.

BACKGROUND OF THE INVENTION

[0002] The typical screen technology in rear projection displaysutilizes a special dark-stripe structure to improve the ambient lightrejection, which effectively provides a higher contrast display. Thisdark-stripe structure is simply an array of blackened vertical stripes,separated by regions allowing light to pass through. These regionsallowing light to pass through, whether they may be transparent,translucent, diffuse, or another type of structure, will be referred toherein as clear stripes or simply stripes or structures allowing lightto pass. For CRT based displays these screens work fine. However forpixelated (digital) displays, which utilize digital spatial lightmodulators (SLM) such as the micromirror device (DMD) or LCD technology,the current dark-stripe structure can interfere optically with thepixelated structure of the SLMs, causing interference fringes known asmoiré patterns.

[0003]FIGS. 1a and 1 b are top and front drawings, respectively, of atypical dark-stripe, or dark-stripe rear-projection screen. The backsideof the screen, where the projected image enters, consists of a layer ofsmall lenticular lens elements 10. The dark-stripe structure isfabricated on the opposite surface (from the lens elements) of thelenticular layer and consists of vertical black stripes 11 separated bytransparent (clear) stripes 12. Next, a diffusion layer 13 is put on topof the dark-stripe layer to diffuse the light 15, coming through thetransparent stripes 12, across the entire screen 150-154. Finally a hardcoating layer 14 is applied on the outside surface of the screen forprotection purposes.

[0004] In operation, the black stripes 11 tend to make the screen lookdark to the viewer while still letting light pass through it. Thisprovides adequate picture contrast for viewing in a room with ordinarylighting conditions (although not intended for use in direct sunlight).

[0005] In these display screens, the lenticular lens elements 10 areoptimized to direct most of the available light to a viewing spotdirectly in front of the screen, where a typical viewer is likely to belocated. As the viewer moves away from this central viewing point,either vertically or horizontally, the brightness will graduallydecrease.

[0006]FIG. 2a is a Fourier transform of a continuous-time signal andFIGS. 2a and 2 b are Fourier transforms of discrete-time signalsobtained by periodic sampling this continuous signal, which illustratewhat causes the moiré fringes in digital displays. In FIG. 2b thesampling period for the screen is large (low sampling rate), so that theperiodic repetitions of the continuous-time transform (FIG. 2a) overlap.In this case, the upper frequencies in Xa(jΩ) (FIG. 2a) get reflectedinto the lower frequencies in X(_(e) ^(jω)) (FIG. 2b) in the overlappedareas. This phenomenon, where in effect the high frequency component inthe continuous time signal takes on the identity of a lower frequency,is called aliasing and causes moiré fringes to occur. On the other hand,in FIG. 2c the sampling period for the screen is small enough (highsampling rate) so that the periodic repetitions of the continuous timetransform do not overlap and therefore moiré fringes do not occur.

[0007]FIG. 3 is an example of the moiré effect 32. This illustrationinvolves overlaying one pixelated pattern 31 over a second pixelatedpattern 30 and slightly rotating the patterns relative to each other toestablish the overlapping conditions discussed in FIG. 2b.

[0008] The pitch (spacing between lines) of dark-stripe screens iscontinuously getting smaller as screen technology advances, but so arethe display pixels, so that moiré effects will continue to be a problem.What is needed is a method to provide a step-function improvement toovercome this problem. The disclosed invention accomplishes this byrotating the dark-stripe structure relative to the displayed pixels.

SUMMARY OF THE INVENTION

[0009] This invention discloses a method for reducing the moiré effectin rear-projection displays by rotating the dark-stripe structure in thescreen 45±15 degrees relative to the vertical axis of the display. Byrotating the black stripes relative to the display pixels, the spatialfrequency at which the moiré effect sets in can be improved by 15% to41%.

[0010] To prevent the moiré phenomenon from occurring, the Nyquist rateof the screen structure must be less than one-half the pixel rate (asimaged on the screen); that is, the projected pixel pitch is greaterthan twice the screen structure pitch. The method of this inventionextends the ratio of the projected pixel pitch to screen structure pitchby a factor of up to 1.41.

[0011] The lenticular lens elements on the input surface of the screencan be shaped to match the angle of the opening between dark-stripes tomaintain a high brightness level in the center of the screen thatdecreases in the normal sense as the viewer moves in either the verticalor horizontal directions, if desired.

[0012] This method extends the use of existing lower-cost dark-stripescreens to provide high performance displays with reduced moiréinterference and as screen technology advances with finer dark-stripepitch, will continue to provide between 15% and 41% improvement overconventional vertical stripe screens.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] For a more complete understanding of the present invention, andthe advantages thereof, reference is now made to the followingdescriptions taken in conjunction with the accompanying drawings, inwhich:

[0014]FIGS. 1a and 1 b are drawings showing the top and front views of aconventional dark-stripe rear-projection display screen.

[0015]FIG. 2a is a waveform for a Fourier transform of a continuous-timesignal.

[0016]FIG. 2b is a waveform for a Fourier transform of a discrete-timesignal obtained by periodic sampling the continuous waveform of FIG. 2a,for the case where the sampling period is large so that the periodicrepetitions of the continuous-time transform overlap, resulting in amoiré fringes.

[0017]FIG. 2c is a waveform for a Fourier transform of a discrete-timesignal obtained by periodic sampling the continuous waveform of FIG. 2afor the case where the sampling period is small enough that the periodicrepetitions of the continuous-time transform do not overlap andtherefore do not cause moiré fringes to occur.

[0018]FIG. 3 is a sketch illustrating the moiré effect where onepixelated pattern is laid over a second pixelated pattern and slightlyrotated to generate the moiré fringe pattern.

[0019]FIGS. 4a and 4 b are drawings showing the top and front views ofthe dark-stripe rear-projection screen of the present invention, wherethe dark-stripe structure is rotated 45±15 degrees relative to thepixels being displayed on the screen.

[0020]FIGS. 5a and 5 b are drawings illustrating the pixel pitch vs.screen structure pitch for a conventional dark-stripe screen and therotated dark-stripe screen of the present invention, respectively.

[0021]FIG. 5c is a graph illustrating the trigonometric improvement inpixel pitch to dark-stripe pitch realized by rotating the dark-stripestructure in the method of the present invention.

[0022]FIGS. 6a and 6 b show lenticular lens elements for the rotateddark-stripe screen of the present invention, where the lens elements areshaped to reduce the brightness roll-off along the horizontal screenaxis.

[0023]FIG. 7 is a drawing of a rear-projection display, which uses therotated black-strip display screen of the present invention.

[0024]FIG. 8 illustrates the pixel pitch vs. screen structure pitch fora conventional dark-stripe screen combined with an image produced by anarray of diamond-shaped pixels.

[0025]FIG. 9 illustrates the pixel pitch vs. screen structure pitch fora conventional dark-stripe screen combined with an image produced by astaggered pixel array.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] This invention discloses a method for reducing the moiré effectin rear-projection displays by rotating the dark-stripe structure in thescreen 45±15 degrees relative to the displayed pixels or the axes of thedisplay. By rotating the dark-stripes relative to the displayed pixels,the spatial frequency at which the moiré effect sets in can be improvedby 15% to 41%.

[0027]FIGS. 4a and 4 b are drawings showing the top and front views ofthe dark-stripe rear-projection screen of the present invention, wherethe dark-stripe structure is rotated 45±15 degrees relative to the axesof the screen. The backside of the screen where the projected imageenters, consists of a layer of small lenticular lens elements 40. Thedark-stripe structure is fabricated on the opposite surface (from thelens elements) of the lenticular layer and consists of diagonal blackstripes 41 separated by transparent (clear) stripes 42. However, in thiscase the dark-stripe structure is rotated from 45±15 degrees relative tothe vertical axis of the screen. Next, a diffusion layer 43 isfabricated on top of the rotated dark-stripe layer to diffuse the light45, coming through the transparent stripes 42, across the entire screen450-454. Finally a hard coating layer 44 is applied on the outsidesurface of the screen for protection purposes.

[0028] In operation, the rotated black stripes 41 tend to make thescreen look dark to the viewer while still letting light pass throughit. This provides adequate picture contrast for viewing in a room havingordinary lighting conditions.

[0029] In these display screens the lenticular lens elements 40 areoptimized to direct most of the available light to a viewing spotdirectly in front of the screen, where a typical viewer is likely to belocated. However, in this case the maximum roll-off in brightness willoccur as the viewer moves away from this central viewing point in adiagonally manner. Although this has proven to be acceptable, thelenticular lens elements can be shaped to cause the maximum brightnessroll-off to occur in the vertical and horizontal directions, if desired.

[0030] To prevent moiré patterns from occurring in dark-striperear-projection screens the conditions stated in the following equationmust exist:

[0031] Projected Pixel Pitch≧2× Screen Structure Pitch, where screenstructure pitch is defined as the distance between black stripes on thescreen and projected pixel pitch as the distance between the projector'spixels as imaged on the screen.

[0032] Another way of saying this is that since the screen pitch must be≦one-half the projected pixel pitch, then the sampling rate (1/pitch) ofthe screen, generally referred to as the Nyquist rate, must be ≧2 theprojected pixel rate.

[0033]FIGS. 5a and 5 b are drawings illustrating the projected pixelpitch vs. screen structure pitch for a conventional dark-stripe screenand the rotated dark-stripe screen of the present invention,respectively. In FIG. 5a, the projector's pixels are defined by the darklines 50, while the screen's dark-stripe structure is shown by theshaded/white columns 52/53. In this drawing, the projected pixel pitch51 is 2 times the dark-stripe pitch 54; e.g., the projected pixel pitch51 may be 1 mm and the dark-stripe pitch 54 0.5 mm. Therefore, thescreen sampling rate is 2 times the pixel sampling rate, thereby justsatisfying the Nyquist rate so that moiré patterns would not beintroduced. However, since the pixel pitch of many newer Spatial LightModulators is being reduced, the impact of moiré using the samedark-stripe screen may increase and become objectionable. As thescreen's dark-stripe structure is made finer as in the case of futuremore expensive screens, there is greater margin before the Nyquist rateis exceeded and moiré effects become evident.

[0034] However, as shown in FIG. 5b the Nyquist rate can be improved forthe same black-strip screen of FIG. 5a by rotating the dark-stripestructure relative to the displayed pixels. In this example, the pixelsare defined by the dark lines 55 and the dark-stripe structure bydiagonal shaded/white stripes 57/58, which is rotated 45° relative tothe pixels. The dark-stripe pitch 59 is the same (0.5 mm) as in theearlier example, but the pixel pitch 56 is now 1.4 mm, or 41% greaterthan for the vertical stripe example. The means that a given screen hasup to a 41% greater margin against moiré effects, for the rotateddark-stripe structure of the present invention, over the conventionalvertical dark-stripe structure.

[0035]FIG. 5c is a graph showing the trigonometric relationship realizedby rotating the dark-stripe structure in a rear-projection screen. Inthis graph, the length of lines 500, 501 represents the pixel pitch fora conventional vertical dark-stripe screen, while the length of lines510, 520, and 530 represent the effective pixel pitch for the rotateddark-stripe screen of the present invention, where the structure isrotated 30° 5100 and 45° 5200 relative to the vertical axis or 30° 5300and 45° 5201 relative to the horizontal axis. Normalizing the length ofthese vectors so that lines 500, 501 for a conventional screen is 1.0,then the length of lines 510, 520, and 530 for the rotated dark-stripestructure of the present invention are 1.15, 1.41, and 1.15,respectively. This represents a maximum improvement in the Nyquist rateof 41% when the dark-stripe structure 57 is rotated 45° and 15% whenrotated 30° relative to either the vertical or the horizontal axis ofthe screen.

[0036] The trigonometric functions to establish this improvement isgiven as follows:

[0037] For rotations of 30 to 45 degrees from the vertical axis of thescreen,

[0038] cosine (θ)=L₍₅₀₀₎/L_((θ)), so that for

[0039] L₍₅₀₀₎=1 and angle (5100)=30°, then

[0040] L₍₅₁₀₎=L₍₅₀₀₎/cosine (30°)=1.0/0.866

[0041] L₍₅₁₀₎=1.155, or for

[0042] L₍₅₀₀₎=1 and angle (5200)=45°, then

[0043] L₍₅₂₀₎=L₍₅₀₀₎/cosine (45°)=1.0/0.707

[0044] L₍₅₂₀₎=1.414; and

[0045] for rotations of 30 to 45 degrees from the horizontal axis of thescreen,

[0046] cosine (θ)=L₍₅₀₁₎/L_((θ)), so that for

[0047] L₍₅₀₁₎=1 and angle (5300)=30°, then

[0048] L₍₅₃₀₎=L₍₅₀₁₎/cosine (30°)=1.0/ 0.866

[0049] L₍₅₃₀₎=1.155, or for

[0050] L₍₅₀₁₎=1 and angle (5201)=45°, then

[0051] L₍₅₂₀₎=L₍₅₀₁₎/cosine (45°)=1.0/0.707

[0052] L₍₅₂₀₎=1.414.

[0053] The lenticular lenses tend to project a majority of the availablelight directly in front of the center portion of the screen where theviewer's eye is normally located. As the viewer moves about, the screenbrightness is observed to roll-off. For the rotated dark-stripestructure of the present invention, this roll-off will be morepronounced along the diagonals from corner-to-corner of the screen.Although this diagonal roll-off is no more objectionable than thevertical and horizontal roll-off in conventional screens, theoptimization of the vertical and horizontal components is no longerpreserved to maintain the original viewing angles. The lenticular lenselements 60-65 and 600-605 shown in FIGS. 6a and 6 b can be shaped tomaintain the traditional brightness roll-off relative to the verticaland horizontal screen axes.

[0054]FIG. 7 is a drawing of a rear-screen projection display, whichuses the rotated dark-stripe screen of the present invention. Theprojector is housed in a free-standing cabinet 70 and includes aprojection engine 72, a relative large turning mirror 73, and therotated black-strip rear-projection screen 71 of the present invention.The engine 72 can use any pixelated technology, although the exampleshown is for a digital micromirror device (DMD) projector. The engine 72is located in the lower portion of the cabinet 70 and uses a single DMD724 to modulate the light. This particular configuration of the engine720 is comprised of a light source 720, which emits white light along afirst light path, through a motor-driven rotating color filter wheel721, which provides sequential red-green-blue (R-G-B) light. Thissequential light is collected by an integrating rod 722 and passedthrough a condensing lens 723 where it is sized to fit the aperture of atotal-internal-reflective (TIR) prism 725. The light is reflected off aninternal surface of the TIR prism on to the reflective mirrors of theDMD 724 where it is modulated and projected back through the TIR prism725 along a second light path, through a projection lens 726 andprojected 741 (shaded area) on to the rather large turning mirror 73positioned diagonally along the upper back surface of the cabinet 70, asshown. This sequential R-G-B light is then reflected 751 (shaded area)off the turning mirror 73 through the rotated dark-stripe screen 71 forviewing by an observer. This shows one configuration of one type enginethat can be used with the screen of the present invention. Other DMDengine may not involve a TIR prism and/or an integrating rod. Otherengines technologies, such as LCD, are also applicable, as areprojectors using two or three spatial light modulators.

[0055] Typical pixel pitch at the screen for a projected image in a DMDrear-projection system is about 1.0 mm based on the projection lens 726having a magnification of 72× and a 57-inch diagonal image with 16:9aspect ratio. This corresponds to an effective pitch of 1.4 mm for therotated dark-stripe screen of the present invention. The margin againstmoiré fringes will become more critical as the pixels become smallerrelative to the black stripe pitch in future projection systems.

[0056] The dark-stripe rear-projection screen 71 is that of the presentinvention, where the dark-stripe structure is rotated 45±15 degreesrelative to the displayed pixels and/or the axes of the screen. Thebackside of the screen, where the projected image enters, consists of alayer of small lenticular lens elements 710. The dark-stripe structureis fabricated on the opposite surface (from the lens elements) of thelenticular layer and consists of diagonal black stripes 711 separated bytransparent (clear) stripes 712. In this case the dark-stripe structureis rotated 45±15 degrees relative to the displayed pixels. Next, adiffusion layer (not shown) is fabricated on top of the rotateddark-stripe layer to diffuse 752 the light 751, coming through thetransparent stripes 712, across the entire screen. Finally a hardcoating layer is applied on the outside surface of the screen forprotection purposes.

[0057] In operation, the projector presents sequential R-G-B images tothe screen 71 at a rate sufficient that the eye integrates the image toprovide a high-performance color picture. The rotated black stripes 711tend to make the screen look dark to the viewer while still lettinglight pass through it. This provides adequate picture contrast forviewing in a room with ordinary lighting conditions.

[0058] Where desirable, the lenticular lens elements can be shaped tocause the brightness roll-off in the screen to occur in the vertical andhorizontal directions. This screen 71 improves the margin for preventingmoiré patterns from occurring by effectively increasing the pixel pitchto screen structure pitch ratio by a factor of up to 1.41.

[0059] While the present invention has thus far been discussed in termsof the preferred method of aligning the dark stripe structures of thedisplay screen diagonally across a pixelated image formed by verticalcolumns and horizontal rows of pixels, it should be understood that analternate embodiment provides vertical or horizontal-from the viewer'sperspective-dark stripe structures to prevent or reduce the moiré effectwhen an image formed by a staggered array of pixels is projected. FIGS.8 and 9 show such arrangements.

[0060] In FIG. 8, an array of diamond-shaped pixels 80 is provided. Thediamond-shaped pixels 80 are arranged in an array such that each pixelis offset in the horizontal direction from the pixels in the rowsimmediately above and below. A portion of the display screen 82 issuperimposed on the array of diamond-shaped pixels 80. As in priorembodiments, the display screen is comprised of alternating clear 83 anddark 84 stripe structures arranged at a rate of at least twice thehorizontal pixel resolution. As in the previous embodiments, diagonalrelationship between the dark screen structures 84 and the diagonalpixels tends to reduce the moiré effect. While the embodiment of FIG. 8reduces the moiré effect, the diagonal pixels often produce noticeablejagged edges on vertical lines and therefore are often less desirablethan the typical orthogonal array of pixels shown in FIGS. 5a and 5 b.

[0061] In FIG. 9, a staggered array of pixels is used. The staggeredarray of pixels 90 is comprised of rows of rectangular pixels, each rowoffset in the horizontal direction from the rows immediately above andbelow. A portion of the display screen 92 is superimposed on the arrayof diamond-shaped pixels 90. As in prior embodiments, the display screenis comprised of alternating clear 93 and dark 94 stripe structuresarranged at a rate of at least twice the horizontal pixel resolution. Asin the previous embodiments, diagonal relationship between the darkscreen structures 94 and the diagonal pixels tends to reduce the moiréeffect. While the embodiment of FIG. 9 reduces the moiré effect, thediagonal pixels often produce noticeable jagged edges on vertical linesand therefore are often less desirable than the typical orthogonal arrayof pixels shown in FIGS. 5a and 5 b.

[0062] The embodiments shown in FIGS. 8 and 9 each provide pixel arrayswith strong diagonal orientations. These pixel arrays form diagonalgroups of pixels having abutting sides-in contrast with traditionalorthogonal arrays in which diagonal pixels merely touch at the corners.By orienting the dark-structures of the display screen at an angle of45±15 degrees relative to the diagonal groups of pixels having abuttingsides the moiré effect is reduced.

[0063] While the present invention has been described in the context ofpreferred embodiments, it will be apparent to those skilled in the artthat the present invention may be modified in numerous ways and mayassume embodiments other than that specifically set out and describedabove. Accordingly, it is intended by the appended claims to cover allmodifications of the invention that fall within the true spirit andscope of the invention.

What is claimed is:
 1. The method of reducing the moiré effect, themethod comprising: providing an image projector for projecting an imagebearing beam of light along an image path; and providing a displayscreen on said image path such that said image bearing beam forms animage comprised of a plurality of rows of pixels when said image bearingbeam strikes said display screen, said display screen having a pluralityof light impeding stripe structures oriented 45±15 degrees relative tosaid rows of pixels in said image.
 2. The method of claim 1, whereinsaid providing an image projector comprises providing an image projectorprojecting an image bearing beam of light forming an image comprised ofan orthogonal array of pixels arranged in rows and columns.
 3. Arear-projection display screen comprising: a lenticular lens layerhaving shaped lens elements for receiving modulated light; a dark-stripelayer attached to said lenticular lens layer, said dark-stripe layercomprising a plurality of dark-stripes separated by stripes allowingsaid modulated light to pass through said dark-stripe layer, saiddark-stripes rotated 45±15 degrees relative to an edge of said screen.4. The display screen of claim 3 comprising: a diffusion layer attachedto said dark-stripe layer.
 5. The display screen of claim 3 comprising:a diffusion layer attached to said dark-stripe layer opposite saidlenticular lens layer.
 6. The display screen of claim 3 comprising: adiffusion layer attached to said dark-stripe layer; and a hard coatingapplied to said diffusion layer to protect said screen.
 7. The displayscreen of claim 3 wherein said rotated dark-stripe structure maintainsthe contrast of said screen while providing a margin against moiréeffects in said screen by a factor of 1.15 to 1.41, relative to adisplay screen having a 0 degree rotation angle.
 8. The display screenof claim 3, wherein said shaped lens elements are orientated to optimizethe brightness and viewing angle of said screen in the vertical andhorizontal directions.
 9. The display screen of claim 3, wherein saidshaped lens elements are orientated to increase the viewing angle ofsaid screen in the horizontal direction.
 10. The display screen of claim3, wherein said shaped lens elements are staggered to follow theorientation of said stripes allowing said modulated light to passthrough.
 11. A display, comprising: a projection engine projecting animage bearing beam of light along a light path, said image borne by saidimage bearing beam of light comprised of a plurality of rows of pixels;a display screen positioned to receive said image bearing beam of light,said screen having a dark-stripe structure rotated 45±15 degreesrelative to said rows of pixels.
 12. The display of claim 11 comprising:a cabinet housing said projection engine and attached to said displayscreen.
 13. The display of claim 11 comprising: a fold mirror on saidlight path.
 14. The display of claim 11, said display screen comprising:a lenticular lens layer having shaped lens elements for receivingmodulated light; a dark-stripe layer attached to said lenticular lenslayer, said dark-stripe layer comprising a plurality of dark-stripesseparated by stripes allowing said modulated light to pass through saiddark-stripe layer, said dark-stripes rotated 45±15 degrees relative toan edge of said screen.
 15. The display of claim 14 comprising: adiffusion layer attached to said dark-stripe layer.
 16. The display ofclaim 14 comprising: a diffusion layer attached to said dark-stripelayer opposite said lenticular lens layer.
 17. The display of claim 14comprising: a diffusion layer attached to said dark-stripe layer; and ahard coating applied to said diffusion layer to protect said screen. 18.The display of claim 14 wherein said rotated dark-stripe structuremaintains the contrast of said screen while providing a margin againstmoiré effects in said screen by a factor of 1.15 to 1.41, relative to adisplay screen having a 0 degree rotation angle.
 19. The display ofclaim 14, wherein said shaped lens elements are orientated to optimizethe brightness and viewing angle of said screen in the vertical andhorizontal directions.
 20. The display of claim 14, wherein said shapedlens elements are orientated to increase the viewing angle of saidscreen in the horizontal direction.
 21. The display of claim 14, whereinsaid shaped lens elements are staggered to follow the orientation ofsaid stripes allowing said modulated light to pass through.
 22. Thedisplay of claim 11, said projection engine comprising at least oneliquid crystal device.
 23. The display of claim 11, said projectionengine comprising at least one digital micromirror device.
 24. Thedisplay of claim 11, said projection engine comprising: a light sourceemitting white light; a rotating color filter wheel filtering said whitelight and emitting sequential red-green-blue light; and a digitalmicromirror device modulating said sequential red-green-blue light. 25.The display of claim 11, said projection engine comprising: a lightsource emitting white light along a light path; an integrating rod alongsaid light path; a rotating color filter wheel filtering said whitelight and emitting sequential red-green-blue light; a digitalmicromirror device modulating said sequential red-green-blue light; atotal internal reflective prism on said light path directing saidsequential red-green-blue light onto and off of said digital micromirrordevice.
 26. A display, comprising: a projection engine projecting animage bearing beam of light along a light path, said image borne by saidimage bearing beam of light comprised of a plurality diagonal groups ofpixels having abutting sides; a display screen positioned to receivesaid image bearing beam of light, said screen having a dark-stripestructure oriented 45±15 degrees relative to said diagonal groups ofpixels having abutting sides.
 27. The display of claim 26 comprising: acabinet housing said projection engine and attached to said displayscreen.
 28. The display of claim 26 comprising: a fold mirror on saidlight path.
 29. The display of claim 26, said display screen comprising:a lenticular lens layer having shaped lens elements for receivingmodulated light; a dark-stripe layer attached to said lenticular lenslayer, said dark-stripe layer comprising a plurality of dark-stripesseparated by stripes allowing said modulated light to pass through saiddark-stripe layer, said dark-stripes rotated 45±15 degrees relative toan edge of said screen.
 30. The display of claim 29 comprising: adiffusion layer attached to said dark-stripe layer.
 31. The display ofclaim 29 comprising: a diffusion layer attached to said dark-stripelayer opposite said lenticular lens layer.
 32. The display of claim 29comprising: a diffusion layer attached to said dark-stripe layer; and ahard coating applied to said diffusion layer to protect said screen. 33.The display of claim 29 wherein said rotated dark-stripe structuremaintains the contrast of said screen while providing a margin againstmoiré effects in said screen by a factor of 1.15 to 1.41, relative to adisplay screen having a 0 degree rotation angle.
 34. The display ofclaim 29, wherein said shaped lens elements are orientated to optimizethe brightness and viewing angle of said screen in the vertical andhorizontal directions.
 35. The display of claim 29, wherein said shapedlens elements are orientated to increase the viewing angle of saidscreen in the horizontal direction.
 36. The display of claim 29, whereinsaid shaped lens elements are staggered to follow the orientation ofsaid stripes allowing said modulated light to pass through.
 37. Thedisplay of claim 26, said projection engine comprising at least oneliquid crystal device.
 38. The display of claim 26, said projectionengine comprising at least one digital micromirror device.
 39. Thedisplay of claim 26, said projection engine comprising: a light sourceemitting white light; a rotating color filter wheel filtering said whitelight and emitting sequential red-green-blue light; and a digitalmicromirror device modulating said sequential red-green-blue light. 40.The display of claim 26, said projection engine comprising: a lightsource emitting white light along a light path; an integrating rod alongsaid light path; a rotating color filter wheel filtering said whitelight, and emitting sequential red-green-blue light; a digitalmicromirror device modulating said sequential red-green-white light; atotal internal reflective prism on said light path directing saidsequential red-green-blue light onto and off of digital micromirrordevice.